Polymerization of gaseous hydrocarbons



LE: ROY. G. STORY Pomnuim.zATIoN QF GAsEous HYDRocARBoNs LEROY G. STORYINVENTOR Patented Jas.- 3, 1939 ,PATENT OFFICE roLmnIzArioN or GAsEo'Usmnocsnnons Le Roy G. Story, White Plains, N. Y., assigner to The TexasCompany, New York, N. Y., a corporation of Delaware Application December28, 1936, Serial No. 117,794

^4Claima This invention relates to the treatment of cracked hydrocarbondistillates to produce an improved yield of antiknock gasolinetherefrom.

'I'he invention contemplates the treatment of 5 cracked hydrocarbondistillates including gasoline hydrocarbons and normally gaseoushydrocarbons below the gasoline boiling point range, by subjecting,thedistillate to contact with a solid adsorbent catalytic material, toeiiect polymerization of undesirable gum forming constituents,separating from the treated products a puriiied gasoline condensate andthen subjecting the normally gaseous hydrocarbons containing polymer-v 1izable unsaturated constituents to catalytic polya merization in thepresence of a polymerizing catalyst to convert the unsaturatedconstituents into additional gasoline hydrocarbons.

It is commercial practice to subject cracking polymerization in thepresence of a catalyst, such as phosphoric acid, or one havingsubstantially the properties of phosphoric acid, to polymerize theunsaturated constituents of the gas to hydrocarbons within the gasolineboiling range. In such an operation, however, gummy, resinous or tarryproducts often accumulate in the catalyst and diillculty may beencountered in maintaining the catalyst in an active condition.Furthermore,

the resultant polymer naphtha often contains substantial amounts ofunstable constituents which require further rening of the polymer bytreating operations such as acid treating or contact with a solidadsorbent material such as fullers earth.

It has been found that improved results may be obtained if the crackedhydrocarbon distillate, containing the normally gaseous hydrocarbonswhich are to be thereafter subjected to catalytic polymerization, iscontacted with a solid adsorbent catalytic material to remove the moreuny ystable constituentsthereof. In accordance withthe'presentinvention, the cracked hydrocarbon distillate which contains in additionyto gasoline 45 hydrocarbons, normally gaseous hydrocarbons below the`gasoline boiling rang/e, is subjected to rening treatment by contactwith a solid adsorbent such as fullers earth, whereby Athe unstable orgum forming constituents are polymerized. `In

`50 this way the unstable constituents of the gasoline `are polymerizedLand separated whereby a relatively stable gasoline condensate may beobtained, and also undesirable unstable constituents are polymerized andremoved from the normally gas- 55 eous hydrocarbons to prodlle im??Mable still or unsaturated refinery gases to catalytic (ci. 19e-1o) 'icharging stock for the catalytic polymerization operation.

The invention will be more fully understood from the followingdescription read in connection with the accompanying drawing which showsa 5 sketch of one type of apparatus for carrying out the process of theinvention.

In practicing the invention with an apparatus such as Athat shown in thedrawing, a cracked distillate containing' gasoline `hydrocarbons andv 10normally gaseous hydrocarbons below the gasoline boiling. range, isconducted through the line I, controlled by valve 2, to a fractionator3. The cracked distillate so introduced may be in the form of vaporderived from an adjacent still for producing or rerunning crackeddistillates. In the fractionator lit vis preferable that vapors beseparated into an overhead fraction of maximum boiling range ofapproximately that of the nal are' ordinarily the maximum. The pressure,of

course. will depend on the type of still from which the vapors arederived. Overhead vapors from the fractionator 3 pass through the vaporline 1 30 controlled by valve 8 in whichis located a superheater 9, to aclay treater I0. A super-heater may be used to raise the temperature ofthe vaprs when it is desired to maintain a higher temperature in theclay vapor treater than is possible by the normal temperature of thevapors introducedthereto.

The purpose oi' the clay treater is to eii'ect removal of undesirableunsaturated constituents such as those normally tending vto polymerizeto40 i form color and gum constituents on storage. Al-

though I have shown means for carrying out this.` clay treatment in thevapor phase, it is intended that either liquid or partial liquid andvapor phase treatment may be used. The type of treatment will dependlargely on the temperatures and pressures employed and if suillcientsuperatmospheric pressure is used, the hydrocarbons may be largely inthe liquid condition. The clay treater I0 shown in the drawing is theconventional type for the clay vapor treatment of cracked distillatesand consists of an insulated shell containing a man- .hole l2 forintroducing solid adsorbent catalytic material I3 which rests on aperforated bottom' I4. The solid adsorbent may be iullers earth,

silicagehorshnilarcommonlyused forthispurpose. 'Ihevaporspassdownwardiythrough the catalytic material and through the perfontions in the plateIl tothe outlet line Il. Anoutletllpe II controlled byvalveIlisprovidedforremovingthespentclayfromthetreater; The polymerid ginnformingV constituents whichanddraininto thebottomofthetreatermaybewithdrawnthroughthelinell controlled byvalve 2l.

The condiiiom maintained in the clay treater may be tenperatures of400-700" F. and pressures substantiallythe same as those in fractionator3, or somewhat lower. Pressures oi 10o-750 and preferably around 200-500pounds are satisfactory. It is intended that the treatment in thetreater Il will remove suiilcient of the unstable constituents toproduce a relatively stable gasolinecondensateofgoodcolor,andalsotoremove t of the lmstable constituents from these lytic polymerization, astrong polymerizing catalystwillnotbeundulyimpairedandahighquality-polymer naphtha will be produced. In some casa.conditions ordinarily employed in the clay vapor treatment of crackednaphtha distillates will be suitable for the purposes of the presentinvention. However, in some cases, it may be desirable to maintainrather drastic conditions of temperature and pressure in the claytreater whereby a substantial amount of the normally is polymerized intonormally liquid and resinous materials. The purpose of the clay vaportreatment having been stated, one skilled in the art will be able tomaintain conditions in the clay treater which will give the desiredresults.

Theclaytreatedvaporsand gasesareconducted from the clay treater throughthe line I to a condenser coil 2i, wherein the normally liquid hy arecondensed and conducted through the run-down line 26. controlled byvalve 21 to an accumulator Il. The pressure on the accumulator may behigher or lower than that maintalnedintherestofthesystem andmaybecontrolled by regulating valve 21 and valve 3L in the gas release line32, communicating with tbe top of the accumulator.K The pressuremaintained ai the acclnnulator will determine the amoimt and characterof the gases which are released therefrom. Ordinarily all the hydrogenandmethaneareseparatedandreleasedas gases from the accumulator andpreferably in addition l thereto all or a portion of the Czhydrocarbons, and evensomcoftheCshydrocarbonsmaybe liberated. Thecontaining the gasoline constituents and the remaining normally gaseousare withdrawn from the accumulator' and conducted through the valvecontrolledline Iltoa'stabiliser 8|. In this stabiliser the' condensateVis fractionated and a. gasolineornaphthaofthedesiredvaporpressin'ewithdrawn from the bottom thereof through the valve controlled line 3l.Ordinarily the condmsate so withdrawn contains no substantial amount oi'hydrocarbons and may be partially orentirelydevold ofCr. The normallygaseous hydrocarbons separated from the distillate are ranoved from thestabiliser through the vapor line Il.

'111e normally gaseous predominatingincaandcrhydrocarbons whlchareseparated from the clay vapor treated cracked disiillateinthestabilinerl! shouldbesubstutially free from undesirable, imstable, gum-formingconstituents and contain a considerable portion of unsaturatedconstituents which are suitable for catalytic polymerization. 'lhesegasesv are conducted through the line 40 to a heating coil Il located ina furnace 42. In this coil the gases under a pressure of 50-500 poundsand preferably under a pressure of about 1D0-200 pounds are heated to atemperature of 30o-600 F. and preferably around 400-500 F. The vaporsare conducted from the heater through transfer line Il to catalysttreater 4S wherein they contact the active polymerizing catalyst, suchas phosphoric acid. Ordinarily this catalyst is in a solid state, suchas a mixture of phosphoric acid and fullers earth, suitably disposed inthe chamber to eii'ect intimate contact between the vapors and thecatalyst. While phosphoric acid catalyst is preferred, it is to beunderstood that other polymerizing catalysts such as aluminum chloride.sulfuric acid, etc., may be used. It is intended that in this catalysttreater a. major portion or substantially all of the unsaturated or olenhydrocarbons are polymerized to normally liquid hydrocarbons, preferablywithin the gasoline boiling range. Ordinarily when the crackeddistillate has received proper treatment, in the preliminary clay vaportreatment as described heretofore, the polymerization of the olens inthe catalyst treater should proceed smoothly without substantial orgreatly reduced impairment of the active polymerizing catalyst.

The products from the catalyst treater l5 are conducted through thetransfer. line 48 to a fractionator I8. In this fractionatorsubstantially all the normally liquid hydrocarbons are separated anddrawn from the bottom thereof through valve controlled line 49. If thepolymerization has proceeded properly, the remaining normally gaseoushydrocarbons should be largely paramnic and may be released from the topof the fractionator through the valve controlled line l0. It isordinarily desirable, however, to retain as much of the C4 hydrocarbonsin the polymer naphtha as is feasible for obtaining a blended gasolineof desired Reid vapor pressure. In some cases it may be desirable torecycle the polymer naphtha to the system and in this instance more ofthe normally gaseous hydrocarbons than ordinarily may be retained in thepolymer naphtha, especially if a substantial amount of unsaturatedconstituents which are desirable for further treatment, is included.

For the purpose of recycling the polymernaphlthaalinel!inwhlchislocatedpump llisprovided. By closing valve Bi inline l! and opening valve M in line 62, the polymer naphtha may beretin-ned by way of lines I! and l1 either to the stabilizer 38 or bythe way of lines I! and 60 'to the clay vapor treater I0. In case it isdesirable only to stabilize the polymer naphtha and obtain a ilnishedblended gasoline, the valve l. in the line 51 may be opened and thepolymer returned tolthe stabilizer and commingled with the treatedcracked distillate to obtain a finished gasoline of high antiknock valuefrom the stabilizer. In case it is desirable to obtain a highlystabilized product from the system, it maybe advantageous to give thepolymer naphtha a. clay vapor treatment. In order to do this the valveIlinthe line Il maybe closed andthevalve It in the line 60 opened andthe polymer naphtha forced to a. heat exchanger 6I wherein it may bepartially or entirely vaporized and then introduced into the claytreater in conjunction with clay treated products were cooled tocondense substantially all but the products low-er than the C3hydrocarbons and the uncondensed gases separated from the liquids. Thecondensate was then subjected to 'further fractionation or stabilizationto separate the C3 hydrocarbons and a portion of the C4 hydrocarbonsfrom the stabilized distillate. The normally gaseous hydrocarbonspredominating in C3 and C4 hydrocarbons and containing a substantialamount of unsaturated constituents,

were heated to about 450 F. under a pressure of about 100 pounds andsubjected to polymerization in the presence of a mixture of phosphoricacid and fullers earth. The polymerized products were fractionated toseparate a polymer naphtha which was subsequently blended with the clayVapor treated cracked distillate. Approximately 35% of the normallygaseous hydrocarbons is converted into high antiknock polymer naphthaand when combined with the clay vapor treated cracked distillate astable gasoline of around 70 octane number is obtained.

The present invention provides a unitary process for producing animproved yield of high quality gasoline from cracking stock; also newand improved results by clay treating the cracked distillate containingthe normally gaseous hydrocarbons are obtained. Not only is the crackedgasoline purified but at the same time the gases are also conditionedwher eby they may be catalytically polymerized to produce an improvedquality of polymer naph'tha with substantially less impairment ofA theefficiency of the active polymerizing catalyst.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims. l Y

I claim:

1. A process for the treatment of cracked distillates, includinggasoline hydrocarbons and normally gaseous hydrocarbons below thegasoline boiling-point range, which comprises subjecting the distillateto contact with solid adsorbent catalytic material to effectpolymerization of undesirable gum forming constituents, separating fromthe treated products a liquid fraction containing constituents withinthe gasoline boilingpoint range, also separating from the treatedproducts a normally gaseous hydrocarbon fraction containingpolymerizable unsaturated constituents, then subjecting said gaseoushydrocarbon fraction to polymerization in the presence of a catalyst ofsubstantially the polymerizing properties of phosphoric acid wherebysaid unsaturated constituents are polymerized to normally liquidhydrocarbons and recycling the products from the last mentionedpolymerization operation to the first mentioned polymerizatio operation.

2. A process for the treatment of cracked distillates, includinggasoline hydrocarbons and normally gaseous hydrocarbons below thegasoline V boiling-point range, which comprises subjecting thedistillate in vapor phase to'contact with solid adsorptive catalyticmaterial to eect polymerization of the more unstable constituents whichtend to polymerize to gummy and resinous materials, separating from thetreated vapors a liquid condensate containing gasoline constituents,also separating from the treated vapors a normally gaseous fractionpredominating in hydrocarbons of between 2 andv 5 carbon atoms andcontaining polymerizable olefins, subjecting said normally gaseoushydrocarbons to the action of a polymerizing catalyst of substantiallythe polymerizing properties of phosphoric acid whereby said olens arepolymerized to normally liquid hydrocarbons of gasoline boiling-pointrange, stabilizing said normally liquid hydrocarbons and recycling thestabilized product to the first mentioned polymerization operation. i

3. A process for the treatment of cracked distillates, includinggasoline hydrocarbons and nor-- mally gaseous hydrocarbons below thegasoline boiling-point range, which comprises subjecting the distillatein vapor phase to contact with solid adsorptive catalytic material toeffect polymerization of the more unstable constituents which tend topolymerize to gummy and resinous materials, separating from the treatedvapors a liquid condensate containing gasoline constituents, alsoseparating from the treated vapors a normally gaseous fractionpredominating in hydrocarbons of between 2 and 5 carbon atoms andcontaining polymerizable olefins, subjecting said normally gaseoushydrocarbons to the action of a polymerizing catalyst of substantiallythe polymerizing properties of phosphoric acid .whereby said oleiins arepolymerized to normally liquid hydrocarbons of gasoline boiling pointrange, and returning the normally liquid hydrocarbons for treatment bysaid solid adsorbent catalytic material.

4. A process for the manufacture of antiknock motor fuel, whichcomprises subjecting a cracked distillate, containing gasolinehydrocarbons and normally gaseous hydrocarbons below the gasolineboiling point range, to partial polymerization in the presence of asolid adsorptive catalyst whereby the more reactive constituents thereofare polymerized, fractionating the treated products to obtain a stablegasoline, subjecting the gaseous hydrocarbons to polymerization in thepresence of a polymerizing catalyst of the phosphoric acid type topolymerize oleiins in said gases to gasoline polymers, separating anunstabilized polymer naphtha from the polymerization products andrecycling said polymer to said partial polymerization operation.

LE ROY G. STORY.

